Merchandisers having anti-fog coatings and methods for making the same

ABSTRACT

A variety of refrigerators and merchandisers having glass or plastic substrates that are substantially fog-resistant are provided. For example, refrigerator doors having a substantially transparent substrate including an anti-fog coating on at least a portion thereof are provided. The portion of the substrate may substantially not fog when the portion has an initial surface temperature and is then exposed to a moist air ambient with a dewpoint temperature equal to or greater than the surface temperature for a period of time. The surface temperature may be less than about 0° C. and the period of time may be greater than about 6 seconds.

CROSS-REFERENCE TO RELATED APPLICATIONS

This patent application is a continuation of prior application Ser. No.11/454,247, filed on Jun. 16, 2006, which is a continuation of priorapplication Ser. No. 10/341,525, filed on Jan. 13, 2003, which claimsthe benefit of priority of prior filed co-pending provisional patentapplication No. 60/377,334 filed on May 2, 2002. The subject matter ofeach of these applications is hereby fully incorporated by reference.

BACKGROUND OF THE INVENTION

Low temperature merchandisers for frozen foods are designed to maintainproduct temperatures in the display area less than about 0° C., and moreparticularly, less than or equal to about −15° C. for frozen food andbelow about −24° C. for ice cream, which in the past have requiredcooling coil temperatures in the range of about −24° C. down to about37° C. Low temperature merchandisers are generally kept at temperaturesless than about 0° C., and more particularly below −21° C. Mediumtemperature merchandisers maintain non-frozen food items, attemperatures generally in the range of about −1° C. to about 5° C.

Multi-shelf reach-in merchandisers for the storage and display of freshand frozen food products (including ice cream) provide a generallyvertical display of the product for greater visibility and productaccessibility to shoppers. In order to prevent the escape of cold airinto the shopping arena, a transparent glass or plastic front doortypically closes the display area of the merchandisers. Glass andplastic are poor thermal insulators. As a result, the doors areconventionally formed by two or three spaced apart panes of glass,defining one or two air spaces to increase the thermal insulation of thedoor. The air spaces must be sealed for maximum insulating effect, andto prevent entry of moisture into these air spaces. Moisture in the airspace condenses on the cold glass (or fogs) and obscures viewing of theproduct in the merchandiser. In the past, sealing of the air space hasbeen accomplished by forming an “insulating glass unit” or “IG unit”(sometimes called a “glass pack”) which consists of opposing glass panes(called “lights” or “lites”) separated by a metallic spacer secured by asuitable polymer (e.g., polysulfide, polyisobutylene, etc.). The glasspack is placed in a metal frame to complete the door. Thus, the doorassembly process usually has involved two separate steps of forming thesealed air spacers because it has a good strength-to-weight ratio. Inaddition, metal is an excellent moisture barrier and when used as aspacer seals the air space from moisture for many years. However, metalhas two important drawbacks when used in reach-in-doors. The first isthat metal is a poor thermal insulator, and the second is that metal isan excellent electrical conductor.

Conventional attempts to attenuate thermal conduction through the metalin the door generally involve placing barriers in the path of thermalconduction. Others have attempted to partially or entirely replace themetal frame with a polymeric material having a substantially lowerthermal conductivity. However, it will be noted that in these attemptsto reduce the metal used in the doors have not eliminated the metallicspacers, nor have they replaced the need for sealing glass lites beforeforming the frame.

The electrical conductivity of metal has also been a hindrance becausein the past electrical power was commonly used to heat one or moresurfaces of the glass lites in the door in order to prevent condensationfrom collecting and obscuring vision through the glass or plastic panes.For instance, the moisture in the relatively warm ambient air of thestore readily condenses on the outside of the door if it was not heated.Also, when the door is opened, moisture condenses on the cold insideglass surface. Without heating, this condensation would not clearquickly and so the view of the product in the merchandiser would beobscured. Typically, two types of heaters have been used: (1) ananti-sweat heater wire is applied to the perimeter of the metal frame;and (2) a semi-conductive coating or film (e.g., fluorine-dopedtin-oxide) on the inner surface of the outer glass lite in the door ispowered by bus bars along opposing edges of the lite to provide anelectrical potential causing a current to flow through theelectrically-conductive film and produce heat. It has been necessary tokeep wiring and bus bars supplying the electric power carefullyinsulated and isolated from the outer metal door frame and the innermetal spacer. This means that a portion of the heating film had to beeliminated at the edge margin where there would be contact with metal.Avoiding electrical wiring and heating is desired.

Therefore, new ways are sought of preventing or inhibiting fogging ofglass or plastic substrates when a door is exposed to a cool environment(as discussed above and in more detail below), and is then exposed tomoist air ambient conditions upon being opened. The cool inside surfaceof a refrigerator door may be exposed to an ambient environment for afew seconds, thirty seconds, or longer, depending on how long thecustomers or employees keep the door open. In other words, new ways tooptimize visibility for the marketing of frozen food products aresought.

SUMMARY OF THE INVENTION

The invention provides a variety of fog-resistant coatings that can beused in a variety of applications. More particularly, the inventionprovides a variety of refrigerators and merchandisers including glass orplastic substrates having coatings thereon, rendering the substratessubstantially fog-resistant.

In one aspect, for example, the invention provides a refrigerator doorcomprising a substantially transparent substrate having an anti-fogcoating on at least a portion thereof. The portion of the substrate maynot substantially fog when the portion has an initial surfacetemperature and is then exposed to a moist air ambient with a dewpointtemperature equal to or greater than the surface temperature for aperiod of time. The surface temperature may be less than about 0° C. andthe period of time may be greater than about 6 seconds.

In another aspect, the invention provides a refrigerator door comprisinga substantially transparent substrate having a polyurethane coatingthereon. The coating may have a surface tension of less than about 60dynes/cm.

In yet another aspect, the invention provides a method of manufacturinga refrigerator door having a substantially transparent substrate. Themethod includes mixing an isocyanate with a polyol to form a mixture,applying the mixture to at least a portion of the substantiallytransparent substrate, and then curing the mixture. The substrate may bepart of a refrigerator door or the substrate may be used to manufacturea refrigerator door.

DESCRIPTION OF THE DRAWINGS

In the accompanying drawings that form a part of this specification andwherein like numerals refer to like parts wherever they occur:

FIG. 1 is a perspective view of a refrigerated reach-in merchandiser;

FIG. 2 is a fragmentary perspective view of reach-in doors andassociated door casing of the merchandiser;

FIG. 3 is a greatly-enlarged fragmentary sectional view of a three litereach-in door taken in the plane of line 3-3 of FIG. 2, and illustratinga preferred embodiment of a no-heat door having both a hydrophilic filmand low-E glass;

FIG. 4 is a fragmentary edge-on elevational view of a spacer member forthe reach-in doors, laid out flat and showing a metal moisture sealingtape exploded above the spacer;

FIG. 5 is a fragmentary perspective view from a corner of the spacer asinstalled on the glass lites, and partially exploded to illustrate theassembly of the spacer ends by a spacer locking key for the door;

FIG. 5A is a fragmentary perspective view from the opposite side fromFIG. 5;

FIG. 6 is a side elevation of the spacer locking key for the spacer;

FIG. 6A is a greatly enlarged fragmentary view of the spacer locking keytaken from the right side of FIG. 6;

FIG. 7 is a fragmentary elevational view of the upper corner of thereach-in door and door casing, with parts broken away to show details ofconstruction;

FIG. 7A is a fragmentary elevational view of the lower corner of thereach-in door and door casing, with parts broken away to show details ofa torsion rod and lower hinge construction;

FIG. 8 is an exploded view showing a torsion rod adjustment feature ofthe door;

FIG. 8A is cross-sectional view of FIG. 8, taken along line 8A-8A;

FIG. 9 is a view of the spacer as assembled around the glass lites, andis broken away to illustrate the no-heat coating applied to the exposedsurface of the inner lite; and

FIG. 10 is a view of the spacer and glass lites from the side oppositeto FIG. 9 to show the outer lite exposed to the ambient environment, andis broken away to illustrate a low-E coating applied to the innersurface thereof.

DETAILED DESCRIPTION OF THE INVENTION

A wide variety of refrigerators, refrigerator doors, and merchandisersmay be used in conjunction with the present invention. Moreparticularly, the coatings disclosed below may be used in conjunctionwith existing merchandisers using heaters (as described above), or withmerchandisers having no heaters. Examples may include, but are not to belimited to, the refrigerated merchandisers disclosed in U.S. Pat. Nos.6,148,563 and 6,401,399, each of which issued to Roche, and each ofwhich is hereby fully incorporated by reference. The following is adescription of one particular embodiment of a merchandiser orrefrigerator, upon which the coatings may be used. As used herein,“merchandisers” and “refrigerators” may be used interchangeably. Again,the coatings may be used with any refrigerators or merchandisers, andshould not be limited in application to the following example.

FIG. 1 shows one example of a low temperature reach-in merchandiser,which is indicated generally at M for disclosure purposes. Themerchandiser has an outer insulated cabinet having a front opening 11(FIG. 2) defined by a cabinet casing C and closed by doors D hingedlymounted on the casing C. More particularly, the reach-in door D ismounted on the door casing C of the refrigerated merchandiser M forswinging motion between a closed position in which the door covers theencased front opening 11 in the cabinet 10 (center door in FIG. 2), andan open position for access to the refrigerated display zone 13 withinthe cabinet (left door in FIG. 2). Multiple shelves 12 are selectivelyprovided in the cabinet to hold and display product in the refrigeratedinterior product zone 13. As shown in FIG. 2, the doors Dare opened byhandles H to access the refrigerated zone 13 inside the merchandiserwhere product is held for display. The refrigerated zone 13 may beilluminated by lighting L mounted on mullions 14 of the door casing C.These lights L are covered by diffusers 15 which spread the light withinthe merchandiser display area 13, as will be described more fullyhereinafter.

FIG. 3 shows in more detail the low temperature door including threepanes, lites or substrates G of glass, namely an inner lite 17, a middlelite 18 and an outer lite 19 that are assembled and held together by themolded frame F. In a typical three lite panel, the glass surfaces aregenerally sequentially numbered from 1 to 6 starting from the outermostambient store or customer side. These correlate to the three lites 19,18 and 17 as surfaces 19 a, 19 b, 18 a, 18 b, 17 a and 17 b,respectively (FIG. 3). The precise number of lites may differ, buttypically at least one, and more typically, at least two lites may beused in the door. The anti-fog coatings described herein may be appliedusing application techniques discussed in more detail below on anyportion of any of the three lites. Typically, however, the anti-fogcoatings described herein are applied on the exposed inner surface 17 bof the inner lite 17 next to the low temperature product area 13 (FIGS.2, 3 and 9).

The refrigerators used herein may also selectively utilizelow-emissivity (Low-E) glass in combination with the inner glass 17having an anti-fogging film 80. Use of low-E is not limited to thisparticular embodiment. One or more of the lites (17, 18, or 19) maycomprise low-E glass or have low-E coatings thereon (as described inmore detail below), and in the three-lite door D of FIG. 3 both lites 18and 19 may be provided with low-E coatings 85. Although any of thesubstrates 19 a, 19 b, 18 a, 18 b, 17 a, 17 b may comprise low-E glassor be coated with a low-E coating (i.e. have low-E properties), mosttypically at least one of substrates 19 b, 18 a, 18 b, and 17 a willhave low-E properties. In one example, substrates 19 b and 18 b may havelow-E properties, while in another example, substrate 18 a and 17 a maypossess low-E properties. Alternatively, substrates 19 b and 17 a maycomprise low-E glass or have a low-E coating thereon. The lites may ormay not be heated. Accordingly, the efficacy of the door to resistfogging and/or to maintain high transparency may depend on the characterand application of the surface coating described above (together withthe no-metal door frame now to be described).

The glass or plastic lites are held in parallel spaced apart, generallyface-to-face positions relative to each other by a spacer S to form abasic glass panel subassembly preliminary to molding the frame F.Referring to FIGS. 3 and 4, the spacer may be made of polypropylene, orother suitable material, which has low thermal and electricalconductivity in a three lite door, two separator or spacer body portions21 of the spacer S are inwardly disposed between adjacent pairs of theglass lites (i.e. 17,18 and 18,19), and these portions 21 are joinedtogether by an integral, unitary outer wall portion 22. The number ofseparator portions depends upon the number of glass lites to be spacedby the separator portions. Each separator or spacer body portion 21 hasa generally D shaped or rectangular configuration with spaced side walls21 a connected by a free inner wall 21 b opposite to the outer wallmember 22. The side walls 21 a are engaged in surface contact withrespective glass lites (17,18 or 18,19) adjacent to the free edgemargins 23 thereof. In addition, a sealing lip 23 a may be providedalong the juncture of the outward side wall and free wall (21 a, 21 b)of each spacer body 21 as an additional assurance of continuous sealingengagement of the spacer bodies 21 with the respective inner surfaces 17a,19 b of the outermost glass lites 17,19. Continuous sealing contact ofthe spacer around the lites prevents molded material from encroachingthe sealed air spaces 23 b between adjacent lites during formation ofthe door frame F.

The planar-outer wall 22 forms one wall of each spacer body 21 and has aconnecting web 22 a between the spacer bodies and also projectslaterally outwardly to form flanges 22 h at the outer longitudinal edgesof the spacer. The laterally projecting flange portions 22 b abutagainst the outer peripheral edge margins 23 of the inner and outerlites 17,19 in the door for additional sealing and also to maintain thespacer in position under frame molding pressure. Still referring to FIG.3, the spacer bodies 21 are typically hollow (24), but filled with asuitable desiccant material 24 a (e.g., molecular sieve) for trappingmoisture.

Referring to FIG. 4, the spacer S is a flat extruded strip with fourangle-cut or chamfered notches 25 being formed in the spacer body 21corresponding to the four corners of the basic glass panel for the doorD. The spacer S forms an outer peripheral covering for the three lites17, 18, 19 by coming together at the corners (in the fashion of a miterjoint) when the spacer is assembled around the lites so that the spacersegments extend continuously along the sides and mate together throughthe corners. The spacer S is constructed with five sequential segmentsidentified in FIG. 4 as 26 a-26 e, and being interconnected at the anglecuts 25 by the continuous outer wall 22. Clearly, when the spacer S isfolded or bent during assembly with the glass lites, the two alternateshort segments 26 b and 26 d will be in opposed relation and form theshort horizontal top and bottom walls of the panel. The long segment 26c will define the long vertical wall margin of the panel that willbecome the outer free (unhinged) handle margin of the door, and the tworemaining segments 26 a and 26 e at the free ends 25 a of the strip willclose the inner hinged vertical margin of the panel and may be joinedtogether by a spacer locking key 30.

As shown best in FIGS. 5, 5A, 6, 6A and 9, the locking key 30 has a mainassembly or locking body section 31 (and originally included anelectrical connector section 32 for conventional electrical heating ofthe inner lite 17). The main locking body section 31 is constructed andarranged to mate with and join the free ends 25 a of the spacer S, andit is configured with spaced separator body portions 31 a and aconnecting wall 31 b with outer flanges to match the configuration ofthe spacer 21. Connector blocks or keys 31 c project longitudinally fromboth ends of the separator bodies 31 a, and these are sized to fit intothe hollow cavities 24 of the spacer bodies 21 (FIGS. 5, 5A and 6A). Inaddition, the inner wall 21 b of the spacer bodies 21 have an orifice 31d adjacent to their free edge 25 a, and each key 31 c has a chamferedlocking detent 31 c to snap lock into these holes 3 id and form a secureinterlock therewith. The reach-in door D incorporated a heated glasslite (17) requiring an electrical hook-up that was accommodated throughan electrical connector section 32 and leads 50, 50 a to connectors andbus bars constructed and arranged on the door to provide the electricalheating field across the inner lite 17. However, since a non-heated doorthat still has excellent anti-fogging or rapid clearing action may beprovided, it is possible to eliminate the electrical hook-up for heatingthe inner panel 17 including the protruding electrical connector section32.

The preferred reach-in door embodiment includes moisture barrier tape 33which is applied to the outer surface of the outer wall 22 and flange 22b. This tape 33 may be an aluminum foil tape or, may be a thinsubstantially non-metallic tape of moisture-imperviousmetalized-polyester/polyethylene film that is electricallynon-conductive.

Referring to FIGS. 3, 4 and 5, the tape 33 has a main body 33 a thatcovers the entire outer wall 22 of the spacer S and has an edge wrapthat extends around the outer flange segments 22 b and, preferably, ontothe adjacent outer surfaces of the inner and outer lites 17,19. Thus, asshown in FIG. 4, the tape 33 may be provided as a unitary one-piece mainbody sheet 33 a with integral edge wrap portions (33 b) or as a seriesof main body sheets or segments corresponding to the five sections 26a-26 e of the spacer strip 21. The foil or film sheets 33 a may beapplied to cover the outer wall 22 throughout its length so that theouter spacer wall surface is covered before it is assembled with theglass lites 17-19. In that event, the width of the tape or film would beonly slightly greater than the width of the outer wall 22. The tape maywrap around and under the flanges 22 b and would be in contact with theperipheral edge of the outer lites 17,19 when installed. The locking key30 is also covered with the same film or tape 33 c. The tape 33 providesa non-structural moisture barrier to inhibit significant transfer ormigration of water vapor into the spaces 23 b between the lites.

As indicated, the basic glass panel with assembled lites, spacer andmoisture barrier tape is encased in the outer molded door frame F. Asshown in FIG. 3, this frame F has a main body portion 35 that surroundsthe periphery of the glass panel subassembly, and has an outer wallmargin 35 a and side walls 35 b that extend inwardly and capture theouter glass surface margins (35 c) of the inner and outer lites 17,19.

In use, the reach-in door D is mounted on the door casing C of therefrigerated merchandiser M for swinging motion between a closedposition in which the door covers the encased front opening 11 in thecabinet 10 (center door in FIG. 2), and an open position for access tothe refrigerated display zone 13 within the cabinet (left door in FIG.2). Referring to FIGS. 7 and 7A, the hinge for mounting the door D areaccommodated during the frame molding process by forming an uppercylindrical opening 38 receiving a metal sleeve or bushing 38 a and alower cylindrical opening 39 receiving a sleeve or bushing 39 a. Aftercompletion of molding the frame F around the glass lite subassembly, theupper bushing 38 a preferably receives a plastic sleeve 38 b (FIG. 9) inwhich an upper hinge pin 40 is slidably received for free turningmovement so that this hinge pin is free of any fixed connection to themolded frame F. The bushing 38 a contains a compression spring 40 awhich biases the pin 40 for vertical outward movement relative to theframe F so that the pin projects upwardly to be received into an openingin an upper mounting plate 40 b attached by bolts 40 c to the doorcasing C of the merchandiser M. The bolts 40 c are received throughelongate slots 40 e. Located at offset positions in the upper mountingplate 40 b to permit the upper mounting plate 40 b to be moved laterallyon the door casing. In this way the pivot axis of the door D can beadjusted for optimum alignment within the casing opening.

The upper bushing sleeve 38 a for the upper hinge pin 40 may be part ofan upper reinforcing member 40 g molded into the door frame to rigidifyand strengthen the frame E in the region of the upper door mountingconnection. The member 40 g also provides a hearing portion (41 a) toreceive a pivot pin 41 b to connect one end of a hold open bar 41 to thedoor. The hold open bar 41 limits the maximum angle of opening of thedoor relative to the merchandiser, and functions to hold the door fullyopen when needed (e.g., as for stocking the merchandiser).

As shown in FIG. 7A, the lower hinge pin 43 is provided for during theframe molding process by forming the lower cylindrical opening 39 forthe bushing 39 a, and after the molding process a plastic sleeve 39 h isreceived in the metal bushing as a bearing for the lower hinge pin 43which is free of an fixed connection to the molded frame F. The lowerbushing 39 a may be secured to a lower reinforcing member 43 a forreinforcing the frame F in the door mounting area where the major weightof the door I) is translated to the casing C. The lower end 43 b of thehinge pin projects outwardly below the frame F and is hexagonal (orotherwise shaped) to have a non-rotational fit into a complementaryopening 43 c in a casing bearing plate 43 d bolted at 43 e to the casingC, see FIG. 9A. Thus, the door D will turn on the lower hinge pin 43 asit is opened and closed while the lower hinge pin is stationary relativeto the cabinet casing C.

FIGS. 8 and 8A show torsion rod assembly 144 for self-closing of thedoor. The assembly 144 is accommodated in the vertical opening 39 in themolded door frame F.

The assembly 144 includes an upper torsion housing member 146 moldedinto the frame F, a torsion rod 145 having an upper hook-end 145 breceived in the housing member 146 and a lower end secured on a torquecontrol member 148, and a lower bearing plate 143 d having a toothedratchet opening 143 c therein. In this embodiment the vertical opening139 is created with the sheath 139 a at the time of molding the doorframe, as before.

However, the upper housing member 146 is constructed and arranged toreceive the upper hook-end 145 b of the torsion rod with a sliding fitin the final assembly 144. Thus, the housing member 146 is configured toprovide a tubular section 146 d with a vertical opening 146 a having anend section 146 b to accommodate the sleeve 139 a and an extendedopening 146 c of rectangular cross-section in which the hook-end 145 bis received in a fixed (relatively non-rotational) relationship with thedoor D per se. The housing member 146 is also formed with an integralrigid side section 146 e extending laterally from the tubular section146 d to act as an anchor in the molded frame F.

The hook-end 145 b is bent over to facilitate holding the torsion rod145 from turning about its axis at the upper end within the frame F. Bybending the rod 145 back upon itself, the effective width of the rod isdoubled at the hook-end 145 b. The two contact points of the hook-end145 b which engage the walls of the housing member 146 within theextended opening 146 c are spaced apart for additional mechanicaladvantage in resisting turning about the axis of the torsion rod 145.Although bending of the torsion rod 145 to form the hook-end 145 b isshown, the same effect could be achieved by initially forming the rodwith a flat or wider upper (not shown). For example, the upper end ofthe rod 145 (at least the portion received in the extended opening 146c) could be flattened. The housing member 146 is designed for universaluse with right-hand or left-hand doors and is double-ended with a centerweb 146 f extending across the side section 146 e and through the centerof the tubular section 146 d intermediate of the ends (146 b). Thus, theanchoring housing member 146 can be oriented for the side section 146 eto extend in either direction. The side section 146 e is constructedwith a series of pockets or recesses 146 g defined by spaced webs orribs 146 h to receive a mass of mold material and work with the forceson the housing member to prevent weakening or destruction of the moldedframe, as exerted by the torsion rod 145 during opening and closing ofthe door D through continuous use over long time spans.

The torque control member 148 on the lower end of the torsion rod 145has a saw-toothed ratchet 148 a with typical vertical lock edges 148 band sloping cam surfaces 148 c. A hexagonal or like nut 148 d isintegral or locked to the ratchet 148 a for selective pre-tensionsing ofthe self-closing torque applied to the door. More specifically, prior toinsertion of the ratchet 148 a into the opening 143 c in the lowerbearing plate 143 d, the nut 148 d is turned to twist the torsion rod145 within the bushing 39 a. The ratchet 148 a is then inserted into theopening 143 c, with the teeth of the ratchet engaging the teeth of theopening to hold the torsion rod 145 in a pre-tensioned configuration.

It will thus be seen that the molded door D may eliminate metal framingand provides better insulation and thermal properties in closure of thelow temperature product zone 13. In order to keep the door lites clearof exterior condensation and/or to clear interior condensation after thedoor has been opened, one of the door lites and the inner surface of theouter Tile 19 may be was heated by applying an electrical potentialacross a transparent, electrically conducting film on that innersurface. Alternatively, only the inner surface 17 a of the inner lite 17would be heated and thus the electrically conductive film would beapplied to that surface (17 a). In addition, the space between adjacentlites may be filled with a dry gas, such as argon or krypton, having lowthermal conductivity. The increased thermal resistance of thatarrangement may reduce concern over external condensation. Thus, theheated surface was shifted to the inside lite where it was still neededfor door clearing. It was also believed that that embodiment was moreenergy efficient since only about half the power was required to clearthe door in a commercially acceptable time.

The reach-in door D of this embodiment may or may not have electricalheat applied thereto, but achieves commercially acceptable performancelevels utilizing an anti-fogging coating (described in more detailbelow). The coating may be applied to any portion of the lites 17, 18,19, and may be applied to other interior portions of the refrigerator,e.g., shelves or mirrors. Typically, the coating is applied on theinnermost surface 17 b of the inner lite 17 facing the product zone 13.The anti-fog coatings may be used in conjunction with low-emissivity(low-E) glass or coatings. Use of low-E glass or coatings on the litesis not required, however. A variety of application techniques that arewell-known in the art, some of which are discussed below, may be used onthe doors.

Again, the anti-fog coatings described herein are compatible with anyrefrigeration units having glass, plastic or similar substrates,especially when those substrates are substantially transparent. Theanti-fog coatings work particularly well, however, when used inconjunction with one or more other lites (e.g. 18 and 19) at leastpartially made from or comprising low-E glass or coated with a low-Ecoating. The low-E glass may be selected to meet two primarycriteria: 1) high reflective capability as to the infrared spectrum(thereby rejecting invisible radiant heat); and 2) high visibilitytransmittance (so that it does not obscure or cloud visibility throughit). Low-E coatings typically are “interference” coatings of aboutone-fourth wave length with a emissivity rating from “zero” identifyinga perfect infrared reflector to “one” which would be the leastreflective and undesirable material. There are a large number of suchglass coating materials having varying low-emissivity properties. Clearwindow glass transmits radiation between 0.3 to 2.7 micron wavelength.95% of the energy in blackbody radiation is contained within thisspectrum. The visible spectrum is 0.4-0.7 microns. Infrared radiation is0.7 to 1000 microns. Thus, to reduce radiant heat gain in arefrigerator, it is desirable to reflect the non-visible 0.7 to 2.7micron infrared radiation. Emissivity is the inverse of reflectivity.Thus, a perfect emitter has an emissivity of 1 and reflects nothing.Low-E glass and low-E coated glass or plastic as used herein are meantto refer to glasses or plastics that are designed not to emit (thusreflect) radiation above 0.7 microns. This may be achieved by applying athin coating (typically ¼ the desired wavelength) to the surface of theglass or plastic. More specifically, the low-E glasses and plastics tendto possess a hemispherical spectral emissivity over 0.7, and moreparticularly from 0.7 to 2.7. Typically, several layers are used toreflects greater percentage in the 0.7 to 2.7 micron range. The low-Esurfaces or coatings may have a visible transmittance of about 70% toabout 90%.

Low temperature and normal temperature merchandisers are typically usedin the storage and display of food products merchandised in asupermarket or other food store having a temperature and humiditycontrolled ambient atmosphere. The ASHRAE design ambient for the bestshopper comfort zone is about 24° C. DB (dry bulb) with 55% RH (relativehumidity). A low temperature merchandiser (M) with a product zone (13)temperature of −21° C. will result in a surface temperature of −18° C.on the inner surface 17 b of the inner door lite 17. The resultinggradient across the door to the outer lite 19 depends, in part, on theuse of low-E glass and store environment, but in the above example of24° C. DB and 55% RH, the resultant outer lite surface (19 a) will havea temperature of about 15° C. to 18° C. Thus, it will be seen that thereis some transference of heat across the door D between the store ambientand the cold product zone 13 even when the door is closed and the zone13 is shielded from the store. It is also clear that the ambient heatand humidity will impinge on the cold inner lite surface 17 b when thedoor is opened by a customer, the immediate effect being to tend tocause water condensation (and fogging) on the inner cold surfaces of thedoor (and adjacent casing and into the product zone).

Generally, the door D has an anti-fog coating applied to the exposedinwardly facing surface 17 b of the inner glass lite 17, which mayobviate the need for any electrical heating of any glass lite.Hydrophilic coatings or films may act to increase the surface energy ofthe substrate, thereby causing water condensate to sheet out on thesurface (as opposed to beading up). Thus, the moisture condensation thatoccurs on this exposed cold inner lite surface 17 b when the door D isopened, presents a transparent see-through phenomenon as distinguishedfrom a vision obscuring fog, and rapidly clears. Typical examples ofanti-fog hydrophilic coatings (which may differ from the coatings havinga hydrophobic surface and hydrophilic interior described below) arehydrophilic polyester films and hydrophilic titanium dioxide pyroliccoatings for glass that are compounded and applied to meet certainfavorable performance criteria as compared with typical heated doors.

As indicated, it is desirable that coatings set forth herein produce asubstantially-no-fog result on the inner glass surface 17 b during thedoor opening periods of most shoppers, and this efficacy is enhanced bythe use of low-E glass 85, particularly, for the middle and outer lites18 and 19. The door opening periods may range from a second or two toseveral minutes or much longer. Although the use of two low-E coatingsis disclosed on surface 19 b (#2) of the outer lite and surface 18 b(#4) of the middle lite, it will be understood that the two low-Ecoatings may be applied to surfaces 2 and 5 or surfaces 3 and 5 withequal effectiveness. Further, in instances where the merchandiser M isplaced in higher humidity ambient environments, there will be a greatermoisture condensation on the film surface, in the case of thehydrophilic coatings, which will sheet or spread out evenly and become ano-fog, transparent layer of moisture due to the high affinity ofhydrophilic materials for water vapor. Such a moisture layer will beattracted to the colder interior of the merchandiser and rapidly andevenly absorbed or evaporated therein.

Typically, the hydrophilic materials of the invention produce a hard,smooth impervious coating as through molecular bonding at its interfacewith the glass lite 17. A hardness of about 2 to 8H (pencil hardness) isdesirable. The hydrophilic films depress the freezing point of thatsurface to prevent freezing.

In addition to the hydrophilic coatings, a wide variety of highlyscratch-resistant coatings having a hydrophobic surface and hydrophilicinterior may also be used to inhibit fogging on the substrate of therefrigerator or merchandiser. These coatings may be applied in a similarfashion as discussed above to inhibit fogging, thereby optimizingvisibility for the marketing of frozen foods. For example, polyurethanecompositions may be used. Polyurethane compositions of the presentinvention may be non-fogging and water repellent, and may maintainexcellent abrasion resistance, clarity, and adhesive properties on mostplastics and glass. A hydrophilic layer of the composition possesses awater-repellent surface due to the unique material combinations putforth in the invention. Hydrophilic and water-repellent properties aregenerally achieved without the addition of fog-preventing surfactants orneed for chain extenders. This makes the anti-fog composition superiorto other materials in anti-fog properties. The composition system maycomprise one or more of the following: an isocyanate prepolymer havingreactive or blocked isocyanate groups or a blocked isocyanate, awater-soluble or water dispersible polyol, any compatible organicsolvents or water (and emulsifier, if water-based), any requiredcatalysts, and rheological additives. The invention can be also cast ina solvent-free state in order to produce a film, or casting moldingcomposition.

The coatings, which are the result of curing mixtures that have beenapplied to a substrate, tend to possess permanent, non-foggingproperties and remain hard enough to be used in the everyday situationsrequired in applications such as refrigerator doors, shelves and mirrorswithin a refrigerator, other interior portions of a refrigerator,optical lenses, goggles, shields, sunglasses, windshields, sunroofs,shelves, mirrors etc. These coatings work particularly well when used inconjunction with the low-E glass described above, particularly, in amerchandiser application. By combining a porous, hydrophobic surfacewith a hydrophilic base polymer, it is possible to obtain a compositionpossessing excellent anti-fog characteristics and surface hardness.

Composition hardness and adhesive properties may also be significantlyimproved in order to adapt the coatings to especially difficultsubstrates. Hydrophilic (anti-fog) properties can also be varied to suitthe end product's intended use. Solvent-free, liquid compositions thatcan be used as coatings or in the casting of molded elements, are alsowithin the scope of the invention. The desired properties of thecoatings are discussed in more detail below.

The polymeric composition exhibits excellent surface hardness and waterrepellent properties without the need for chain extenders or surfactantmaterials to provide the desired balance of physical and non-foggingproperties. Although most of the mixtures do not employ surfactants orchain extenders, surfactants and chain extenders may be used in someinstances. Accordingly, many of the coatings described herein are“substantially free” of chain extenders or surfactant materials. In thisinstance, “substantially free” means having less than about 3%, moreparticularly less than about 1%, and more typically, 0.5% to 0% of chainextender or surfactant. The hydrophobic nature of the surface reducesthe presence of water deposited on the surface. Any water that isdeposited thereon may be at least partially absorbed through the poroussurface layers and absorbed into the coating's hydrophilic interior.This combination of hydrophilic and hydrophobic properties provides avery effective non-fogging and scratch resistant surface. Thecomposition system typically comprises an isocyanate prepolymer withreactive isocyanate groups or a blocked isocyanate, and a water-solubleor water dispersible polyol. The system may further comprise, althoughit need not, appropriate organic solvents or water, emulsifiers, andcoalescent, catalysts, and paint additives (typically at levels below 1%by weight). The reaction of the isocyanate and the polyol forms a parthydrophilic and part hydrophobic polyurethane composition when reactedand cured under particular conditions. By varying the type ofisocyanate, the type and molecular weight of the polyol, the percentsolids of the material and the catalyst, the hardness, fog resistance,efficacy, and other physical and chemical properties can be varied.

More specifically, the coating may be the product of the reaction,usually under heat, of an isocyanate prepolymer and a polyalkyleneglycol. Isocyanate adducts and prepolymers particularly effective in theinvention include blocked and unblocked cyclic or aliphaticdiisocyanates. Polyalkylene glycol polymers that may be used includediols, multi-functional variants such as tri- and tetrahydroxy glycols,branched ethylene oxide/propylene glycol copolymers and block polymersof the above. Catalysts may include the common organometallic materialsnormally used to produce polyurethane substances. Specifically, dibutyltin dilaurate may be used as an acceptable catalyst. Other additionsinclude solvents, and rheological additives. The inclusion of catalyticsubstances is pendent on the choice of polymeric functionality and theintended cure schedule. Thus, some materials function well without theusual polyurethane initiators.

These materials are described in more detail below.

Isocyanates

Typically, the isocyanate prepolymers used to prepare the coatingscontain 2 or 3 isocyanate groups, although more groups are certainlyacceptable. Examples of isocyanate systems include a biuret or anisocyanurate of a diisocyanate, triisocyanate or polyisocyanate. Thefollowing are typical diisocyanates prepolymers that may be used:hexamethylene diisocyanate, diisophorone diisocyanate, and toluenediisocyanate. Blocked isocyanates may also be used in order to addressingredient limitations and stability problems.

Mixtures having the blocked polyisocyanates may be applied using any ofthe application techniques discussed herein. Typically, mixtures havingthe blocked polyisocyanates are cured or heated after having beenapplied to a plastic or glass substrate. During heating, the blockedpolyisocyanates dissociate so that the isocyanate groups becomeavailable to react with the active groups of the polyols (discussed inmore detail below), thereby leading to substantial crosslinking andhardening of the coating. Blocked isocyanates are isocyanates in whichat least one isocyanate group has reacted with a protecting or blockingagent to form a derivative which will dissociate on heating to removethe protecting or blocking agent and release the reactive isocyanategroup.

Examples of blocking agents for polyisocyanates include aliphatic,cyclo-aliphatic or aralkyl monobydric alcohols, hydroxylamines andketoximes. Other examples of applicable blocking agent functionalitiesinclude the following: oximes (compounds containing the radical—CH(:N.OH)), pyrazoles, phenols and caprolactams. Typical pyrazoles are4 membered rings having the following formula:

Blocked isocyanates and combinations of the above also produce effectiveformulations.

Most of these blocked polyisocyanates tend to dissociate at temperaturesof about 90° C. to about 180° C. (160° C.). Other blockedpolyisocyanates, however, may dissociate at lower temperatures,especially when used in the company of a catalyst. For example, thetemperature to which the coated article must be heated may generallyfall to about 100 to 140° C. when using the polyisocyanates discussedbelow. The presence of a catalyst may increase the rate of reactionbetween the liberated polyisocyanate and the active hydroxyl group ofthe polyol. Examples of blocked polyisocyanates having a lowerdissociation temperature include compounds having the followingformulas:

R—Y_(m)  FORMULA A

wherein R is a cycloaliphatic, heterocyclic, m valent aliphatic, oraromatic residue and each Y, which may be the same or different, is

Where R₁ is, or, when n is more than 1, each R₁, which may be the sameor different, is an alkyl, alkenyl, aralkyl, N-substituted carbamyl,phenyl, NO₂, halogen or

group where R₂ is a C₁-C₄ alkyl group,

n is 0, 1, 2, or 3

and m is an integer>1, preferably 2-6.

When R₁ represents an alkyl or alkenyl group it may contain up to 4carbon atoms. R₁ may also be an aralkyl group, wherein the aryl portionmay be phenyl and that the alkyl portion may contain 1 to 4 carbonatoms. When R₁ is a halogen, it may typically be chlorine or bromine.

The blocked polyisocyanate of the formula A is formed by admixing thepolyisocyanate

R(NCO)_(m)

with a sufficient quantity of a pyrazole of the formula:

such that the reaction product contains substantially no free isocyanategroups and is a urea of formula I. This reaction is exothermic and sincethe reaction product will dissociate if the temperature is raisedsufficiently, cooling may be required to keep the temperature of thereaction mixture down, preferably to 80° C. or less.

Other blocking agents used in the present invention may be pyrazoles ofthe formula:

where R₁ and n are as defined above. Examples of the pyrazoles include,but are not limited to, 3,5-dimethylpyrazole, 3-methylpyrazole,4-nitro-3,5-dimethylpyrazole and 4-bromo-3,5-dimethylpyrazole.

Some of these pyrazoles can be made by converting acetylacetone (AA)into a derivative that will react with hydrazine to give the desiredpyrazole as shown below:

AA+N_(a)+CH₂═CHCH₂Cl

Ac₂CHCH₂CH═CH₂

AA+N_(a)+PhCH₂Cl

Ac₂CHCH₂Ph

AA+PhNCO

Ac₂CHCONHPh

The polyisocyanate which is to be blocked may be any organicpolyisocyanate suitable for crosslinking compounds containing activehydrogen, e.g., those listed above as well as aliphatics includingcycloaliphatic, aromatic, heterocyclic, and mixed aliphatic aromaticpolyisocyanates containing 2, 3 or more isocyanate groups. The group Rwill normally be a hydrocarbon group but substitution, e.g., by alkoxygroups is possible.

Other blocked isocyanates may include, but should not be limited to,hexamethylene diisocyanate, toluene diisocyanate, diphenylmethanediisocyanate, bis(methylcyclohexyl) diisocyanate, oxime blockedhexamethylene diisocyanate, diethyl malonate blocked toluenediisocyanate. The isocyanate may also be a biurate, e.g., defined as thepartial reaction of a polyisocyanate with hydroxyl or amine componentsto increase terminal isocyanate groups. All isocyanates listed asDesmodur tradenames may also be used, including, Desmodur 75, which is ahexamethylene diisocyanate.

Other isocyanate compounds may be, for example, ethylene diisocyanate,propylene diisocyanate, tetramethylene diisocyanate, decamethylenediisocyanate, dodecamethylene diisocyanate,2,4,4-trimethylhexamethylene-1,6 diisocyanate, phenylene diisocyanate,tolylene or naphthylene diisocyanate, 4,4′-methylene-bis(phenylisocyanate), 4,4′-ethylene-bis(phenyl isocyanate),

-diisocyanato-1,3-dimethyl benzene,

-diisocyanato-1,3-dimethylcyclohexane, 1-methyl-2,4-diisocyanatocyclohexane, 4,4′-methylene-bis(cyclohexyl isocyanate),3-isocyanato-methyl-3,5,5-trimethylcyclohexyl isocyanate, dimeracid-diisocyanate,

-diisocyanato-diethyl benzene,

-diisocyanatodimethyl cyclohexyl benzene,

-diisocyanatodimethyl toluene,

-diisocyanato-diethyl toluene, fumaric acid-bis(2-isocyanato ethyl)ester or triphenyl-methane-triisocyanate, 1,4-bis-(2-isocyanatoprop-2yl) benzene, 1,3-bis-(2-isocyanato prop-2yl) benzene.

These isocyanates are commercially available from manufacturers anddistributors such as DuPont, Dow, Cytec, PPG, Crompton, Bayer, andBaxenden. Typically, the isocyanates that are used have low molecularweights, e.g., hexamethylene diisocyanate and toluene diisocyanate, inorder to maximize the available anti-fog effect. Use can also be made ofpolyisocyanates obtained by reaction of an excess amount of theisocyanate with a) water, b) a lower molecular weight polyol (e.g.m.w.<300) or c) a medium molecular weight polyol, e.g. a polyol ofgreater than 300 and less than 8000 m.w., eg sucrose, or by the reactionof the isocyanate with itself to give an isocyanurate. The lowermolecular weight polyol comprises, for example, ethylene glycol,propylene glycol, 1,3-butylene glycol, neopentyl glycol,2,2,4-trimethyl-1,3-pentane diol, hexamethylene glycol, cyclohexanedimethanol, hydrogenated bisphenol-A, trimethylol propane, trimethylolethane, 1,2,6-hexane triol, glycerine, sorbitol or pentaerythritol, andcombinations thereof.

Polyols

Typical polyols used in conjunction with the invention have a molecularweight of at least about 90, and more particularly at least about 600,and most typically at least about 800. The molecular weight of thepolyols will generally be less than about 30,000, more particularly lessthan about 12,000, even more particularly less than about 4000, andtypically below 1500. The polyols used in conjunction with the inventionmay be straight, branched, or cyclic.

Examples of some of the many possible polyols include polyalkyleneglycols such as polyethylene glycols (PEGs), and polypropylene glycols(PPGs). A general formula for polyalkylene glycols follows: H(OR)_(n)OH,wherein R is an alkyl group and n>10. A general formula for polyethyleneglycols is H(OCH₂CH₂)_(n)OH, wherein n is >2. A general formula forpolypropylene glycol is H(OCH₂CH₂CFH₂)_(n)OH, wherein n is >2.Typically, the polyols are water soluble or dispersible. Block polymersof polyalkylene glycols, and more particularly, block polymers ofpolyethylene glycol and polypropylene glycols may be used. Even moreparticularly, polyethylene-90 or polyethylene-180 may commonly be used.Polyoxyethylene glycols can also be employed.

While a very wide variety of polyols may be used, the typical systemwill employ at least one of polyalkylene glycols, water soluble triols,tetrahydroxy-functional branched ethylene oxide/propylene glycolcopolymers, block polymers thereof, and combinations thereof. Othervariations include water soluble triols or glycerin polymers and othermulti-functional, branched polyhydroxyl compounds such as tetrahydroxyfunctional copolymer of ethylene oxide and propylene glycol, and/orblock polymer combinations of any of the above. Tetrahydroxyfunctional-branched/ethylene oxide/propylene glycol co-polymers may alsobe used.

Catalysts

Catalysts may or may not be employed in conjunction with the mixturesand coatings of the present invention. When used, a wide variety ofcatalysts that are known in the art may be employed. For example,catalysts such as dibutyl tin dilaurate or triethylene diamine may beused. In addition, other catalysts that may be used include, but are notlimited to, the following: amines such as tetramethylbutanediamine;azines such as 1,4 diaza(2,2,2)bicyclooctane; and other organotincompounds such as tinoctoate. These catalysts may facilitate thereaction and may be used to complete the cure of the mixture. Moreparticularly, catalysts may be effective, during heating, to facilitatethe dissociation of the blocked polyisocyanates so that the isocyanategroups become available to react with the active groups of the polyols,thereby leading to substantial crosslinking and hardening of thecoating.

Solvents

The mixtures of the present invention may or may not comprise at leastone solvent. A wide variety of solvents may be used and will beunderstood by those of ordinary skill in the art. For example, tertiarybutyl alcohol, as shown below, may be

Other solvents that may be used include diacetone alcohol, primary andsecondary alcohol. A non-polar solvent that may be used is xylene,although polar solvents tend to work better.

In the case of coatings using reactive isocyanates, non-reactivesolvents such as tertiary butyl alcohol, diacetone alcohol, isophorone,glycol ether EB (2-butoxy ethanol), and the like are used. In thesesystems, the greater part of the solvent mixture is composed of polarsolvents without primary or secondary alcohols. Smaller amounts ofaliphatics, aromatics and other non-polar solvents may then make up theremainder, if so desired.

The systems can be prepared solvent free. This form of the invention maybe used to produce film, cast/molded objects, and co-extruded materials.Using methods well known to the industry, the production of thin films,solids sheets, and monolithic shapes, (i.e., lenses, 3-dimensionalobjects, etc.) is thus possible.

In systems using blocked isocyanates, most solvents are applicable. Anyof various solvents including alcohols, ketones, aromatics, andaliphatics may be used depending upon the specific substrate and/orapplication and curing environments.

Rheological Agents

The mixtures and coatings of the present invention may also compriserheological additives. Rheological agents may be added to increase filmthickness without increasing solids, to stabilize the coatings, controlslip, flow and/or leveling difficulties. Examples of rheological agentsinclude, but are not limited to, ethyl cellulose, methyl cellulose,associative PUR thickeners, anti-mar agents, and combinations thereof.Examples may include DC 28 distributed by Dow Corning, or L-7602 andL-7608 obtained from Crompton of Pittsburg, Pa., some of which arepolyether silicone flow/level agents.

The Mixture

Typically, the mixtures of the present invention comprise the following:

Polyol About 10.0% to about 85.0% by weight; Isocyanate About 15.0% toabout 90.0% by weight; Catalyst About 0.0% to about 2.0% by weight;Solvent About 0.0% to about 95.0% by weight; and Rheological Agent About0.0% to about 2.0% by weight.

These components are weighed out using techniques that are generallyknown in the art. Some or all of the components are then mixed usingsimple mixing, admixing, homogenization, or a combination thereof inorder to form the mixture. This initial mixing is typically performed atambient conditions, namely, ambient temperatures and pressures. Each ofthese mixing techniques is well-known in the art.

The mixtures may then be applied to a variety of substrates using avariety of techniques that are well-known in the art. For example, themixtures discussed herein may be applied directly or indirectly to glassand plastic. In other words, one or more substrates, coatings, layers,or other substances may exist between the mixture (and subsequently, thecoating) and the glass or plastic substrate. As used herein, “applying amixture to a substrate,” “a substrate having a coating” thereon or a“substrate having a coating or at least a portion thereof” may mean thatone or more substrates, coatings, layers or other substances existtherebetween unless otherwise specified. For example, the mixtures orcoatings described herein may be applied to a plastic film (e.g. anacrylic adhesive), wherein the plastic film bonds to the glass orplastic substrate. In addition the mixtures or coatings might be appliedto a low-E plastic film or a substrate. Regarding glass, the hardness,tintability, water repellency, and hydrophilicity are properties toconsider when choosing the glass. On plastics, the properties toconsider are hardness, tintability using hot dye at 90° C., waterrepellency, hydrophilicity, flexibility, thermoformability using heatand/or pressure, and adhesion. Examples of possible plastic substratesinclude, but are not limited to, polycarbonate, allyl diglycolcarbonates or copolymers thereof, acrylic, acrylics, urethanes,polysulfone, polyarylate, PETG, PET, polyolefins, and combinationsthereof. The selection of the base components may be as important. Forexample, the selection of an aliphatic polyurethane base contributes togood resistance to adverse weather conditions and solaraging/ultraviolet rays. Again, using the low-E surfaces and coatingsdiscussed above produces superior results.

The mixtures may be applied to these substrates using a variety oftechniques that are well-known in the art. For example, the mixtures maybe sprayed onto the substrate using high pressure spray applications.Additionally, the substrate may be dipped into the mixture. Flow, spin,curtain, and blade techniques may also be used.

Subsequently, after the mixture is applied to the substrate, the mixtureis exposed to ambient conditions. Typically, the exposure will be forgreater than about one minute, and more particularly greater than about10 minutes. The exposure to ambient conditions after application isgenerally less than about 60 minutes, and more particularly less thanabout 40 minutes. The mixtures are generally exposed to ambientconditions in order to let any solvents in the mixture evaporate.

The mixture is then cured. Typically, the mixture is at least brieflycured at a temperature that is greater than 80° C., more particularlygreater than 100° C., and even more particularly greater than 125° C.Curing is usually performed at temperatures that are less than about180° C., more particularly less than about 135° C., and even moreparticularly less than about 125° C. Curing times may vary. Typically,the mixture is cured for at least about 10 minutes, more particularly atleast about 20 minutes, and even more particularly at least about 40minutes. Curing times are generally less than about 60 minutes, and moreparticularly less than about 40 minutes. Overall, the curing temperatureand time will depend on the substrate's melting point, as well as thetypes and molecular weights of the isocyanate, polyol, blocking agentbeing used. The intended use of the part may also dictate the curingtime and temperature. Again, when using a blocked isocyanate, the curingtime and temperature must be sufficient to enable the blocker todissociate, thereby allowing the isocyanate group to react with thehydroxyl groups and cross-link. Generally, the mixtures that are appliedto the substrates are the result of at least one of the pre-polymersisocyanates at least partially reacting with at least one of thepolyols. The resultant mixture, accordingly, typically comprises across-linked polyurethane.

Alteration of the amount of the individual components, i.e. ratios ofsolvent, polyols, isocyanates, etc. results in products having variablefunctional properties. The coatings and compositions of the presentinvention may possess a variety of chemical and physical properties andfunctionalities.

The resulting cured coating is part hydrophilic and part hydrophobic.More particularly, the surface is substantially hydrophobic, while theinterior is substantially hydrophilic. By combining a porous,hydrophobic surface with a hydrophilic base polymer, it is possible toobtain a composition possessing excellent anti-fog characteristics andsurface hardness. The absorbent polymer coating of the inventionpossesses a water-repellant surface due to the unique materialcombinations set forth in the application. This hydrophobic surface maybe achieved, while maintaining a hydrophilic core layer, bysubstantially excluding surfactants and using higher molecular weightpolyols as discussed herein. Increasing the molecular weight of thepolyols tends to produce increasingly more non-polar polyurethanes afterreaction with the isocyanates discussed above. These higher molecularweight polyurethanes contribute to the water-repellancy of the coatings.

In terms of hydrophobicity, water may run off part of the coating whenapplied to a substrate. Part of the water is actually repelled. Thesurfaces of these particular coatings generally do not tend to sheet andgenerally do not tend to be wet by water. This is due to the surfacetension of the coating, which substantiates the water-repellancy orhydrophobicity of the coatings. Typically, the surface tension of thesurface of the coatings will be greater than about 15 dynes/cm, moreparticularly, greater than about 20 dynes/cm, and even moreparticularly, greater than about 25 dynes/cm. The surface tension istypically less than about 60 dynes/cm, although the surface tension maybe less than about 50 dynes/cm, or even less than about 45 dynes/cm. Thesurface tension of the coatings was tested according to the WilhelmyPlate Method, which is well-known or readily ascertainable by thosehaving ordinary skill in the art.

Cured coatings of the present invention that are products of thereaction of polyols having molecular weights of less than about 600 (seeExample 1 below) may tend to have a surface tension of about 56 to about61 dynes/cm. Polyurethanes made from polyols having molecular weights ofabout 600-800 (see Example 6), about 800-1500 (see Example 4), about1500-4600 (see Example 3), and even about 12,000 tend to have surfacetensions of about 50-57 dynes/cm, about 27-38 dynes/cm, about 23-25dynes/cm and about 21 dynes/cm, respectively. The lower the measurementin terms of dynes/cm, the more hydrophobic the surface. In other words,the low surface tension means that water is actually repelled (i.e. itbeads off), rather than being sheeted or absorbed. Accordingly, by usingpolyols having higher molecular weights, the resulting polyurethanesexhibit more hydrophobic tendencies, at least at the surface.

As discussed above, however, the coatings described herein also have ahydrophilic interior portion. Hydrophilicity may be measured accordingto weight gain the coatings experience upon aqueous immersion. Morespecifically, “hydrophilicity” is a measure of the percent weight gainexperienced by a coating that has been fully immersed in an aqueousmedium for 96 hours at about 20 to 25° C. In other words, during thisperiod, the coating will tend to attract a certain amount of water. Thedifference between the weight of the coating after being immersed andthe weight of the coating before immersion, as expressed as a percentweight gain (as compared to the weight of the non-immersed coating)measures the hydrophilicity of the coating. In other words, thedifference between the mass of the soaked coating and the dry coatingmeasures the hydrophilicity of the coatings. Typically, the coatingsdescribed herein tend to gain greater than about 20% weight, moreparticularly greater than about 30% weight, and often times greater thanabout 35% weight. Weight gain is generally less than about 150%, andtypically the weight gain is less than about 140%, and more particularlyless than about 110%.

As shown in more detail below in the Examples, polyurethanes made frompolyols having a molecular weight around 400 (see Example 1) mayexperience a weight gain of about 140% when exposed to the conditionsdiscussed above. Polyurethanes made from polyols having molecularweights of about 800-1500 (see Example 2) experience a weight gain ofsomewhere between about 75 and about 105%, while polyurethanes made frompolyols having molecular weights of about 4600 may exhibit a weight gainof around 35%. Typically, the higher the molecular weight of the polyolbeing used to form the coating, the less hydrophilic the hydrophilicportion of the coating will be. For the most part, general interpolationmay be used to roughly determine the hydrophilicity of coatingsdiscussed herein based on these numbers.

In addition, the coatings possess excellent anti-fogging characteristicsafter being cured. Accordingly, the coatings are suitable for a varietyof applications including, but not limited to, eyewear, optics,automotive and residential glass surfaces, and flat, sheet stock. Again,the cured anti-fog coatings have the ability to both repel and absorbwater, rather than just sheet water. More particularly, many of thecoatings of the present invention have the ability to pass EN-166,EN-168, and ENE-2205 (analogous to the ASTM D 4060 abrasion testdescribed herein) tests, each of which is a standardized test, thespecifications for which can be obtained from the European Union. Moreparticularly, the coatings described herein may be able to pass theEN-166 test for over a minute, and often times for over five minutes.

Glass or plastic (that is usually transparent) coated with the coatingsdescribed herein tends not to fog when first exposed to a “coolenvironment,” in which the temperature is between about 10° C. to about−25° C., for greater than about thirty seconds and then subsequentlyexposed to humid ambient conditions. At these temperatures, the relativehumidity, of course, will be very low. Even after being exposed to thecool environment as set forth above for more than one minute, many ofthe glass or plastic substrates will not fog regardless of the amount oftime they are exposed to ambient conditions. In more detail, thesubstrates will not fog after being exposed to the cool environment fora minute or more, and then being exposed to ambient conditions for tenseconds, thirty seconds, and even three minutes or more of exposure.Again, many of the coated substrates will not fog after humid ambientexposure for more than five minutes, more than ten minutes, and evenindefinitely after being removed from the cool environment, after havingbeen there for a minute or longer.

More particularly, in one set of experiments, transparent glass andplastic substrates coated with the coatings set forth herein wereexposed to a variety of temperatures falling with the cool environmentfor about one minute, and then were exposed to ambient conditions. Manyof the substrates did not fog after being exposed to the ambientconditions for 10 seconds, thirty seconds, and even three minutes andlonger. Many of the coatings never fogged at all under these conditions.In another set of experiments, different coated transparent glass andplastic substrates were exposed to different temperatures within thecool environment for about five minutes and longer. The substrates werethen removed and exposed to different ambient conditions. The substratesdid not fog after 10 seconds. Many of the substrates did not fog afterthirty seconds, after three minutes, after five minutes, after tenminutes and longer. Again, many of the substrates never fogged.

In addition, portions of substrates that are coated with the anti-fogcoatings may not substantially fog when the coated portion has aninitial surface temperature and is then exposed to a moist air ambientwith a dewpoint temperature equal to or greater than the surfacetemperature for a period of time. More particularly, the substrates maynot fog when the initial surface temperature is less than one or more ofthe following: 20° C., 10° C., 5° C., 0° C., −5° C., −10° C., −15° C.,−18° C., −20° C. and −25° C. The period of time of exposure to thedewpoint temperature equal to or greater than the surface temperaturemay be greater than one or more of the following: 0 seconds, about 1second, about 3 seconds, about 5 seconds, about 6 seconds, about 10seconds, about 30 seconds, about 1 minute, about 2 minutes, about 15minutes, about 30 minutes and about 1 hour. In other words, when coatedsubstrates are first exposed to any of the temperatures or below thetemperatures set forth above, and then exposed to a dewpoint temperatureequal to or greater than the surface temperature for any of the periodsof time set forth above, the substrate may not substantially fog. Notevery coating described herein will prevent fog at each and every one ofthese parameters, although some of the coatings will. The dewpointtemperature that is equal to or greater than the surface temperature mayencompass ambient conditions.

Typically, ambient conditions include any temperature or humidity thatfalls with the ambient temperatures and humidities discussed below.Ambient temperatures include temperatures that are typically greaterthan 10° C., and generally greater than 15° C.

Ambient temperatures are usually less than about 60° C., typically lessthan about 55° C., and more particularly less than about 50° C. Ambientrelative humidities mean some moisture was present in the air. Therelative humidities are generally greater than about 20%, typicallygreater than about 30%, and more typically greater than about 35%. Therelative humidity is typically less than about 100%, more typically lessthan about 95%, and more particularly, less than about 90%. Most typicalof the ambient conditions is about 18° C. to about 30° C. and a relativehumidity about 40 to about 70%. As used herein, “moist ambientconditions” and “moist air ambient” are meant to refer to temperaturesand relative humidities, falling within the ranges of this paragraph,that are most typically associated with the humid ambient conditions ina grocery store, convenience store, or supermarket, or the conditionsimmediately adjacent a beverage cooler. Moisture is typically present inthese conditions. Substrates first exposed to the cool environment maynot fog when exposed to some or all of the ambient conditions.

Curing the mixtures also results in coatings that have excellenthardness characteristics as demonstrated by testing as specified by ASTMD 4060. More particularly, the coatings tend to have a taber haze ofless than about 10% at 100 cycles with 500 gram load and a CS-10F load,and more specifically less than about 5%. Some of the coatings describedherein may have a taber haze of less than about 3% or even about 1%.Typically, known anti-fog coatings exhibit a taber haze of greater than15%. Most polysiloxane hardcoats typically exhibit a taber haze of 3 orgreater.

When testing the coatings according to ASTM 3363 described in moredetail below, the coatings tend to exhibit a hardness of greater thanabout 2H, and typically greater than about 4H. Generally, the hardnessis less than about 8H, and less than about 6H. In this test, thepencil's lower 10-15 mm is trimmed of wood, leaving only the centrallead core extending out of the body of the pencil. Then the lead is heldperpendicular to a flat surface upon which a piece of fine sandpaper ismounted. The protruding section of lead then is abraded at 90°, so as torender the tip of the lead perfectly flat and perpendicular to thepencil's length. The hardness test is performed by applying a pencilhardness tester consisting of a rolling tester weighing 200 g and fixingthe pencil at a 45° angle through the body of the tester and extendingonto the test surface below. The device is moved across the sample (laidflat, horizontally on a hard, level surface) for a distance of about 24mm. As it moves, the pencil's lead (at a 45° angle) will incise/etch ascratch/line into the sample surface if the pencil's graphite/hardnessrating is harder than the sample's coated surface. Hardness is rated asthe hardest lead that does not leave a visible score.

The coatings of the present invention may also have excellent adhesionproperties as indicated by the coatings' ability to pass the ASTM B 3359Method B discussed herein. For example, many of the coatings canwithstand at least one, three and even five pulls with standard Scotchtape 3M 160 on 100 square hatch with no pull up. Moreover, some of thecoatings can even withstand boiling water exposure, and pass 120 minuteadhesion tests.

The coatings also tend to be substantially clear. This property makesthe coatings ideal for substrates that are transparent. In other words,the coatings do not blur or obstruct vision through transparentsubstrates. When applied to transparent substrates, the coatings mayexhibit less than 0.5% detectable haze by hazemeter, more particularlyless than 0.3% detectable haze by hazemeter, and even more particularlyless than 0.2% detectable haze by hazemeter.

The life of the coating, when applied to a substrate, is typicallygreater than about 2 years, but may be greater than about 5 years, andmay even be longer than about 10 years. The shelf-life of the mixturesis also excellent. Compositions may be formulated into single- ordual-component (2K) forms. This allows the selection of unique reactivematerials to suit the various needs of the end product. Typically, theshelf life of the mixtures is at least about 6 months, sometimes atleast about 1 year, and at times at least about 2 years.

The coatings also exhibit exceptional thermoformability. Moreparticularly, the coatings have been applied to substrates and then bentbetween two pieces of curve metal under high heat, more particularly,temperatures greater than about 150° C., and even greater than about180° C. for about 1 to about 2 minutes. The coatings did not crack orlose adhesion properties during this test.

The coatings after being cured tend to have a thickness of at leastabout one-half micron, more particularly greater than about one micron,more particularly greater than about 3 microns, and typically greaterthan about 5 microns. The thicknesses also tend to be less than about 30microns, more particularly less than about 20 microns, and typicallyless that about 15 microns.

Resulting urethanes also accept commercially-available color tints andfunctional solution treatments (i.e. non-fogging, uv-filtration,anti-static) utilized by the retail optical industry.

The present invention is further explained by the following examplesthat should not be construed by way of limiting the scope of the presentinvention.

EXAMPLES Example 1

To illustrate the preparation of an abrasion resistant anti-fog coatingwith a hydrophilic surface. Part A was mixed using simple mixing,namely, a magnetic stir bar and plate with Part B. Part A comprisedabout 28.1 grams Desmodur N-75 (Bayer) well mixed with about 21.9 gramsof diacetone alcohol. Part B comprised about 37.8 grams of diacetonewell mixed with about 11.0 grams PEG-90, 0.2 grams dibutyltin dilaurate,and DC-57 additive (Dow Corning). The mixture was immediately applied toa 4″ square of Lexan polycarbonate, via an airbrush. The mixture wasthen allowed to stand at ambient conditions for about 10 minutes. It wasthen baked for one hour at 125° C. The sample had excellent anti-fogproperties when blown on. A 100-cycle taber abrasion test resulted in ahaze of less than 5% using a dual, 500-gram load and a CS-10F abraserwheel. Note that the light transmittance of the coated sample exceededthe uncoated polycarbonate (approx. 92% before coating application).Separately, each part exhibited a shelf life of over 6 months with noloss of performance properties after mixing appropriately. The pot lifeof the prepared/mixed composition was about 24 to 36 hours. See Table Ifor summarized performance properties.

Example 2

Part A was mixed with Part B using simple stirring, namely, a magneticstir bar and plate to form the mixture. Part A comprised 28.1 grams ofDesmodur N-75 (Bayer) well mixed with 21.9 grams of diacetone alcohol.Part B comprised 35.8 grams of diacetone well mixed with 13.9 grams ofpolyethylene glycol-180, 0.2 grams of dibutyl tin dilaurate, and 0.05grams of DC-57 manufactured by Dow Corning. The mixture was immediatelyapplied by flow-coating to a 4″ square of Teflon coated metal, andallowed to stand at ambient conditions for about 5-10 minutes. Thecooled, cured film was peeled from the teflon surface and wrapped arounda 0.5″ steel rod to observe the flexibility of the film. No crazing ormarring was observed even after wrapping the cured film around itselfmultiple times. The film shows excellent anti-fog properties when blownon or exposed to changes in humidity and temperatures. Condensed watervapor reduces clarity after a few minutes of exposure. The filmexhibited excellent anti-fog properties when blown on, it fills lightscratches produced by 6H pencil, and had exceptional flexibility. Thesecoatings resist cracking when rolled into a circular shape.

See Table I for summarized performance properties.

Example 3

Example 3 illustrates the preparation of a water-repellant, anti-fogcoating for low-temperature usage. In a 1-L beaker equipped with amagnetic stirrer and a heating mantle, about 200 grams Baxenden 7683obtained by Baxenden was stirred with about 281 grams of diacetonealcohol to produce a solution of blocked polyisocyante in solvent. Thesolution was then heated to 60° C. To the heated, stirring solution wasadded a solution of 179 g of PEG-4600 in about 179 grams of diacetonealcohol. The solution was stirred and maintained at 60° C. for about 10minutes. Then 1.6 grams each of dibutylyln dilaurated, and DC-57additive (Dow Corning) were stirred in to produce a coating composition.The heated mixture was then applied to glass panels via flowcoating, andallowed to hang vertically at ambient conditions for 5 minutes. Sampleswere then baked for about 25 minutes at 150° C. Subsequently, thecooled, cured samples were exposed to −25° C. for 10 minutes, and thenexposed to ambient conditions (25° C., 70 to 75% relative humidity) forabout 15 minutes. This was repeated 20 times. The coated glass was foundto maintain clarity and did not collect excessive moisture on its coatedsurfaces. The surface tension was found to be about 23 dynes/sq cmcompared to the untreated glass having a surface tension of about 76-78dynes/sq cm (this quantifies the hydrophobic nature of the surface ofthe invention when prepared with higher molecular weight polyols). SeeTable I for summarized performance properties.

Example 4

To illustrate the preparation of a water repellant, anti-fog coating,about 396 grams Desmodur N-75 (Bayer) was stirred with about 193 gramsof diacetone alcohol in a 1-L beaker equipped with a magnetic stirrer,in order to produce a solution of blocked polyisocyante in solvent. Tothe stirring solution was added a solution of about 147 grams ofPEG-1500 in about 147 grams of diacetone alcohol. Subsequently, about2.2 grams of dibutylyln dilaurate, about 0.5 grams of FC-4430 (3M ofMinnesota) flow/leveling aid, and about 1.0 grams of Silwet L-7602slip/anti-mar agent (Crompton) were added, with stirring, to produce alow-viscosity coating composition. Commercial ADC (allyl diglycolcarbonate, CR-39) panels, 4 inch by 4 inch, were etched, cleaned, andthen dipped into the filtered coating solution using a 4.5 inch/minutewithdrawal rate. Coated samples were then baked for 90 minutes at 105°C. The cured samples were found to perform very well. Surface tensionmeasured after conditioning at about 20-22° C.; 70 to 75% relativehumidity for about 24 hours: 27-29 dynes/sq cm. See Table I forsummarized performance properties.

Example 5

To illustrate another preparation of a water-repellant, anti-fogcoating, a solution of 115 grams of a DEM (diethyl malonate)-blockedhexamethylene diisocyante prepolymer containing 70% solids (Baxenden7963), by weight in methoxypropanol (glycol ether PM) was added to 100grams of 2-butoxethanol (glycol ether EB). To this stirring solution wasadded: 1.1 grams of DBTDL (dibutyl tin dilaurate), 10% in EB. Then, 38.5grams of a monohydroxy,-monobutoxy-functional polypropelene polyglycol(B01/120 form Clariant Germany) and 20.0 grams of a polycaprolactone(CAPA 3091 from Solvay UK) were added. Finally, a solution of 0.8 gramsof DC-57, and 1.5 g. of Silwet L-7608 leveling & air release aid in 150grams of DA were added to complete the coating formulation. Polyamidelenses (trogamid brand) were cleaned, flow-coated with the solution at20° C. and then suspended vertically for 15 minutes to allow solvents topartially evaporate. Coated samples were cured in a convention oven.After 120 minutes at about 109° C., the samples were removed and cooled.Anti-fog properties were excellent, and accelerated weathering (QUV testcabinet from Q-Panel Corp) tests indicated excellent resistance to UVand moisture. See Table I for summarized performance properties.

Example 6

To illustrate the production of a 3-dimensional shape (monolith)exhibiting permanent, intrinsic anti-fog properties. A mixture of about5500 grams of caprolactam-blocked, 100% solids TDI prepolymer product(Baxenden BI 7773), about 1200 grams of PEG-800, and 2220 grams of apolyethylene glycol monomethyl ether having a molecular weight of720-780 (M750 from Clariant) were stirred together at room temperature.To the well-mixed liquid was added about 5.4 g of DBTDL and about 0.5 gof tin diocctoate. The liquid molding composition was cast into arectangular solids measuring 100 cm×100 cm×1 cm thick. The sample wascast between two glass plates that were sealed with a siliconeelastomeric gasket, and cured at 165° C. for 2 hours. After cooling andremoval from the mold, the solidified sample exhibited excellent opticalproperties and good hardness. Non-fogging properties were excellent onall surfaces. The lenses were also tinted and treated to block UV usinga hot (90-92 C) aqueous solution of Electron Beam Gray and UV-Shield(BPI of Miami Fla.). After 10 minutes of exposure, the lenses wererinsed and dried. Luminous transmittance of the gray lenses was lessthan 40%; UV transmittance was <2%. See Table I for summarizedperformance properties.

TABLE I Taber Test Adhesion Pencil Chemical Impact Water Soak - ID LT %¹Haze %² % Haze³ %⁴ hardness⁵ Resistance⁶ Resist⁷ Anti-fog⁸ AF⁹ 1 >97.4<0.5% 4.7 100 6H Fail Acetone PASS Pass 40 s Fall 20 s Pass Others2 >99.1 <0.1 3.9 100 -na- Pass all -na- -na- -na- 3 >98.0 <0.3 1.890/100* 8H Pass all -na- Pass 5 min Pass 5 min 4 >96.8 <0.2 2.2 100 4HFail Acetone PASS Pass 3 min Pass 2 min Fail Xlene Pass others 5 >92.5<0.5 1.1 100 4H Fail isopropanol** PASS Pass 2 min Pass 2 min Passothers 6 >94.3 <0.5 0.78 -na- 5H Pass all PASS Pass Infinite PassInfinite *Example #3, when repeated using an air-dry primer preparedfrom 0.5% Silquest A-1100 in isobutanol. The primer was stirred andsprayed onto the glass substrate. After 30 minutes of air-drying, thecomposition from Example #3 was applied and cured as before. Adhesionwas excellent. **Isopropanol exposure resulted in the appearance ofvisible haze - polyamide substrates are attacked by alcohols. ¹ASTM(American Society for Testing and Materials) E 1348: Test Method forTransmittance by Spectrophotometry using Hemispherical Geometry ²ASTM E284: Reflection Haze ³ASTM D 4060: Method of Abrasion Resistance ofOrganic Coatings - 100 cycles under a dual, 500 gram load using astandard Taber Apraser device [CS-10F Calibrase Abraser wheel] ⁴ASTM D3359 Method B: Standard Test Methods of Measuring Adhesion by Tape Test⁵ASTM D 3363: Test Method for Film Hardness ⁶ASTM D 1308: Test Methodfor Effects of Household Chemicals on Clear Organic Finishes. Chemicalsinclude: isopropanol 70%, acetone, petroleum ether/hexane, xylene,ammonia, acetic acid, hydrochloric acid, Windex, cola/coffee/tea,sweat/saline, and water. ⁷ASTM D 2794: Test for Method of Resistance ofOrganic Coatings to the Effects of Rapid Deformation (Impact). ⁸EN 166European Anti-Fog standard - continuous photometric measurement ofluminous transmittance of sample exposed to fog-conducive environment.Measures point of loss of 20% of clarity. ⁹ASTM D 870: Practice forTesting Water Resistance of Coatings Using Water Immersion. Measure ofAnti-fog performance (w/EN 166) after 96 hours of continual aqueousexposure followed by conditioning at 25° C./70-75% relative humidity for24 hours before testing.

Example 7

Example 7 illustrates the preparation of another water-repellant,anti-fog coating for low-temperature usage. The prepolymer solutionfollows: In a 10-L polyethylene tank equipped with a gear-driven stirrerand an immersion heater, 1948 grams of caprolactam-blocked TDIprepolymer with an equivalent weight of 1395 was stirred with 400 gramsof 4-hydroxy-4-methyl-2-pentanone and 200 grams of 2-butoxy ethanol toproduce a solution of blocked polyisocyante in solvent.

A 3-L dual-necked round-bottomed flask was equipped with a magneticstirrer, reflux condenser, and a heating mantle. A mixture of 855 gramsof powdered PEG-4600 and 200 grams of PEG-1000 was poured into the flaskand 400 grams of tert-butanol was added. Heat was then applied, and thesolution was brought to reflux for 10 minutes to dissolve the PEGsolids. The solution was cooled to 60° C., and then added to theprepolymer solution, with stirring. 2.8 grams of dibutyltin dilaurate(DBTDL) was stirred in for 15 minutes, and then 0.4 g each of L-7602 andL-7608 was added.

The solution was maintained at 50-55° C. via the immersion heater andfiltered through a 0.5 micron cartridge filter. Glass panels weresprayed with a 0.25% of an amino-functional silicone adhesion-promoter(Silquest A-1106) in a 50/50 aqueous solution ethanol. After drying for5 minutes at 20° C., the primed glass was exposed to IR lamps for 15minutes to cure the primed surface, and then allowed to cool to roomtemperature.

The filtered, hot coating solution was applied to the primed glasspanels and allowed to hang vertically at ambient conditions for 25minutes. Samples were cured for 45 minutes at 150° C. via a forced-airconvection oven. After curing, the samples were cooled to roomtemperature. The surface tension was found to be about 29 dynes/sq. cm,and the samples possessed excellent surface hardness.

The prepared samples were exposed to −10° C. for 5 minutes, and thenexposed to a humidity test cabinet maintained at 20° C. and 80% relativehumidity. The coated glass was found to maintain clarity indefinitely,and did not collect excessive moisture on its coated surfaces, i.e., thesurface did not fog. Samples were also saturated in deionized water viaimmersion for 96 hours. After removal from the water, samples weresubjected to low-temperature testing as above. The samples collectedexcessive moisture on their surfaces after 5 minutes of humidity cabinetexposure but did not fog. However, after allowing 30 minutes at 20° C.and 75% relative humidity for the saturated samples to equilibrate/dryout samples performed analogously to the initial test set. See Table IIfor summarized performance properties.

Example 8

Similar to Example 7, 2782 grams of a pyrazole-blocked toluenediisocyanate prepolymer with an equivalent weight of 560 was stirredwith 400 grams of 4-hydroxy-4-methyl-2-pentanone and 250 grams of2-butoxy ethanol to produce a solution of blocked polyisocyante insolvent.

A 3-L dual-necked round-bottomed flask was equipped with a magneticstirrer, reflux condenser, and a heating machine. Powdered PEG-4600,1060 g, was poured in and 400 g of 4-hydroxy-4-methyl-2-pentanone wasadded. Heat was then applied, and the solution was brought to reflux for2 minutes to dissolve the PEG solids. The solution was Cooled to 60° C.,and then added to the prepolymer solution, with stirring. DBTDL 175 g,was stirred in for 60 minutes, and then 0.4 g each of L-7602 & L-7608was added.

The solution was maintained at 50-55° C. via the immersion heater andfiltered through a 1.0 micron cartridge filter. Glass panels weresprayed with a 0.25% of an amino-functional silicone adhesion-promoter(Silquest A-1106) in a 50/50 aqueous solution ethanol. After drying for5 minutes at 20° C., the primed glass was cured for 15 minutes in athermal convection oven at 60° C., and then allowed to cool to roomtemperature. The filtered, hot coating solution was applied to theprimed glass panels and allowed to hang vertically at ambient conditionsfor 15 minutes. Samples were cured for 30 minutes at 125° C. via aconvection oven. Samples were cooled to room temperature.

The samples were then exposed to −20° C. for 10 minutes, and thenexposed to a humidity test cabinet maintained at 20° C. and 78% relativehumidity. The coated glass was found to maintain clarity indefinitely,and did not collect excessive moisture on its coated surfaces. Sampleswere also saturated in deionized water for 96 hours. After removal fromthe water, samples were subjected to low-temperature testing as above.The samples were clear after 5 minutes of humidity cabinet exposure andmaintained clarity indefinitely. See Table II for summarized performanceproperties.

Example 9

Example 9 was conducted as set forth above with respect to Example 7,except that 2-butoxyethanol was replaced with diacetone alcohol (DAA),using the same amount. Example 9 exhibited similar properties to Example7, except Example 9 exhibited superior hardness. This Example shows theeffect solvents have on the final surface hardness. See Table II forsummarized performance properties.

Example 10

Example 10 was conducted as set forth above with respect to Example 9,except the mixture was applied with a spray appliance, which produces amuch thinner coating—about 2-3 microns. The anti-fog results weresimilar to Example 7, however, the coating fogged only after saturationand repetition of low-temperature exposure to test chamber. It did notfog if allowed to equilibrate/dry out. See Table II for summarizedperformance properties.

Example 11

This Example was the same as Example 8, except it was sprayed. Theresults were essentially identical to Example 8. It was a morehydrophilic/anti-fog due to the reduced molecular weight of thepolyol(s), despite thickness variance. See Table II for summarizedperformance properties.

Example 12

This Example was the same as Example 8, except that PEG-1000 in the sameamount was substituted for the PEG of Example 8. In addition,2-butoxyethanol was replaced with 200 g of isophorone, and 2 grams ofDC-57 was added. The coating fogged in 25 seconds upon removal from lowlow-temperature (−12° C. for 5 minutes) and exposure to humiditycabinet. After saturation and soak, the substrate fogged immediatelywhen brought from freezer to test chamber. This shows the effect ofusing a lower molecular weight polyol. See Table II for summarizedperformance properties.

Example 13

This Example was the same as Example 8, except Baxenden BI 7986 (an HDIbiuret blocked with dimethylpyrazole) was substituted for the blockedisocyanate of Example 8. In addition, 1250 grams of PEG 4000 wassubstituted for the PEG of Example 8. This is an example of analternated polyisocyante. See Table II for summarized performanceproperties.

TABLE II Taber Test Adhesion Pencil Chemical Water Soak - ID LT %¹ Haze%² % Haze³ %⁴ hardness⁵ Resistance⁶ Anti-fog⁸ AF⁹ 7 >97 <0.5 6.9 100 6HPass all Pass 5 min Pass 3 min 8 >96 <0.5 1.2 100 10H  Pass all Pass 5min Pass 5 min 9 >99 <0.5 2.1 100 8H Pass all Pass 5 min Pass 3 min10 >99 <0.2 8.3 100 4H Fail Acetone Pass 3 min Pass 1 min Fail XlenePass others 11 >97 <0.5 6.0 100 6H Fail Acetone Pass 3 min Pass 2 minFail Xlene Pass others 12 >93 <0.5 12.8 100 - tacky 3H Fail acetone Pass40 s Fail Pass others 13 >93 <0.3 5.5 100 6H Pass all Not available Notavailable

Example 14

Part A was mixed with Part B using simple stirring, namely, a magneticstir bar and plate to form the mixture. Part A comprised 51.45 grams oftrixene 7683 (commercially available from Baxenden of Lancashire,England) well mixed with 20.67 grams of diacetone alcohol. Part Bcomprised 20.67 grams of diacetone alcohol well mixed with 27.79 gramsof polyethylene glycol 4600 (i.e. PEG having a molecular weight of4600), 0.053 grams of dibutyl tin dilaurate (obtained from Gelest of PA,USA) and 0.037 grams of DC-28 (obtained from Dow Corning). The mixturewas immediately applied using flow-coating to a 4″ square of Tefloncoated metal, and allowed to stand at ambient conditions for about 10minutes. The mixture was then baked for about 1 hour at about 125° C. toproduce the coating.

Example 15

Part A was mixed with Part B using simple stirring, namely, a magneticstir bar and plate to form the mixture. Part A comprised 51.45 grams oftrixene 7683 (commercially available from Baxenden of Lancashire,England) well mixed with 20.68 grams of diacetone alcohol. Part Bcomprised 20.68 grams of diacetone alcohol well mixed with 27.79 gramsof polyethylene glycol 4600, 0.053 grams of dibutyl tin dilaurate(obtained from Gelest of PA, USA), and 0.018 grams of L-7602 (obtainedfrom Crompton of Pittsburgh, Pa., USA) and 0.018 grams of L-7608(obtained from Crompton). These last two components are flow/levelingaids and slip-aids, respectively. The mixture was immediately appliedusing flow-coating to a 4″ square of Teflon coated metal, and allowed tostand at ambient conditions for about 10 minutes. The mixture was thenbaked for about 1 hour at about 125° C. to produce the coating.

Example 16

Part A was mixed with Part B using simple stirring, namely, a magneticstir bar and plate to form the mixture. Part A comprised 42.88 grams oftrixene 7683 (commercially available from Baxenden of Lancashire,England) well mixed with 33.85 grams of diacetone alcohol. Part Bcomprised 33.85 grams of diacetone alcohol well mixed with 23.18 gramsof polyethylene glycol 3000 (i.e. having a molecular weight of 3000),0.053 grams of dibutyl tin dilaurate (obtained from Gelest of PA, USA)and 0.037 grams of DC-28 (obtained from Dow Corning). The mixture wasimmediately applied using flow-coating to a 4″ square of Teflon coatedmetal, and allowed to stand at ambient conditions for about 10 minutes.The mixture was then baked for about 1 hour at about 125° C. to producethe coating.

Example 17

Part A was mixed with Part B using simple stirring, namely, a magneticstir bar and plate to form the mixture. Part A comprised 42.67 grams oftrixene 7683 (commercially available from Baxenden of Lancashire,England) well mixed with 33.75 grams of diacetone alcohol. Part Bcomprised 33.75 grams of diacetone alcohol well mixed with 23.49 gramsof polyethylene glycol 3000, 0.053 grams of dibutyl tin dilaurate(obtained from Gelest of PA, USA) and 0.037 grams of DC-28 (obtainedfrom Dow Corning). The mixture was immediately applied usingflow-coating to a 4″ square of Teflon coated metal, and allowed to standat ambient conditions for about 0 minutes. The mixture was then bakedfor about 1 hour at about 125° C. to produce the coating.

Example 18

Part A was mixed with Part B using simple stirring, namely, a magneticstir bar and plate to form the mixture. Part A comprised 42.88 grams oftrixene 7683 (commercially available from Baxenden of Lancashire,England) well mixed with 33.91 grams of diacetone alcohol. Part Bcomprised 33.91 grams of diacetone alcohol well mixed with 11.56 gramsof polyethylene glycol 3000, 11.56 grams of polyethylene glycol 3000,0.053 grams of dibutyl tin dilaurate (obtained from Gelest of PA, USA)and 0.037 grams of DC-28 (obtained from Dow Corning). The mixture wasimmediately applied using flow-coating to a 4″ square of Teflon coatedmetal, and allowed to stand at ambient conditions for about 10 minutes.The mixture was then baked for about 1 hour at about 125° C. to producethe coating.

Example 19

Part A was mixed with Part B using simple stirring, namely, a magneticstir bar and plate to form the mixture. Part A comprised 42.88 grams oftrixene 7683 (commercially available from Baxenden of Lancashire,England) well mixed with 33.91 grams of diacetone alcohol. Part Bcomprised 33.91 grams of diacetone well mixed with 11.56 grams ofpolyethylene glycol 12000 (i.e. molecular weight 12000), 11.56 grams ofpolyethylene glycol 1000, 0.053 grams of dibutyl tin dilaurate (obtainedby Gelest of PA, USA) and 0.037 grams of DC-28 (obtained from DowCorning). The mixture was immediately applied using flow coating to a 4″square of Teflon coated metal, and allowed to stand at ambientconditions for about 10 minutes. The mixture was then baked for about 1hour at about 125° C. to produce the coating.

Example 20

Part A was mixed with Part B using simple stirring, namely, a magneticstir bar and plate to form the mixture. Part A comprised 35.75 grams oftrixene 7683 (commercially available from Baxenden of Lancashire,England) well mixed with 42.98 grams of diacetone alcohol. Part Bcomprised 42.98 grams of diacetone alcohol well mixed with 21.22 gramsof polyethylene glycol 1000, 0.028 grams of dibutyl tin dilaurate(obtained by Gelest of PA, USA), 0.011 grams of L-7602 (obtained fromCrompton of Pittsburgh, Pa., USA) and 0.011 grams of L-7608 (obtainedfrom Crompton). The mixture was immediately applied using flow-coatingto a 4″ square of Teflon coated metal, and allowed to stand at ambientconditions for about 10 minutes. The mixture was then baked for about 1hour at about 125° C. to produce the coating.

Example 21

Part A was mixed with Part B using simple stirring, namely, a magneticstir bar and plate to form the mixture. Part A comprised 35.75 grams oftrixene 7683 (commercially available from Baxenden of Lancashire,England) well mixed with 42.98 grams of diacetone alcohol. Part Bcomprised 42.98 grams of diacetone well mixed with 21.22 grams ofpolyethylene glycol 1500, 0.028 grams of dibutyl tin dilaurate (obtainedby Gelest of PA, USA), and 0.011 grams of L-7602 (obtained from Cromptonof Pittsburgh, Pa., USA) and 0.011 grams of L-7608 (obtained fromCrompton). The mixture was immediately applied using flow-coating to a4″ square of Teflon coated metal, and allowed to stand at ambientconditions for about 10 minutes. The mixture was then baked for about 1hour at about 125° C. to produce the coating.

Example 22

Anti-fog testing was performed on refrigerator doors having, amongothers, the coating set forth in Example 14. More particularly, testingwas performed on refrigerators having a plurality of adjacent doors withthe coatings thereon. Testing was conducted on both no-heat doors andheated doors. The test conditions for the no-heat doors follow: dry bulbtemperature 75° F.; relative humidity 55%, discharge air temperature−12° F.; door surface temperature on the product side −3° F.; and doorsurface temperature on the customer side of 64° F. The test conditionsfor the heated door follow: dry bulb temperature 75° F.; relativehumidity 55%, discharge air temperature −12° F.; door surfacetemperature on the product side 9° F.; and door surface temperature onthe customer side of 74° F.

When the samples were tested, the coated surface was dry and hadsubstantially no dust accumulation. Visible trans. was about 40 to about50%. Anti-fogging properties were tested at certain time intervals. Moreparticularly, the following time intervals were tested: 6 seconds, 15seconds, 30 seconds, 1 minute, 2 minutes, 2 minutes and 30 seconds, 3minutes, 4 minutes and 5-15 minutes. When coated doors having thesurface temperatures set forth above were opened, and then exposed tothe ambient conditions discussed above, substantially no foggingoccurred at any of these time intervals. Similarly, the doors in therefrigerator adjacent the open door also did not fog during any of thesetime intervals. In other words, when one door was opened, allowingambient air to flood the refrigerator, the closed doors adjacent theopened door exhibited substantially no fogging.

1. A method of manufacturing a refrigerator door having a substantiallytransparent substrate, the method comprising the acts of mixing ablocked isocyanate with a polyol to form a mixture; applying the mixtureto at least a portion of the substantially transparent substrate; andcuring the mixture to form a coating, wherein the substrate is part of arefrigerator door or is used to manufacture a refrigerator door.
 2. Themethod of claim 1, wherein the blocked isocyanate comprises at least oneof hexamethylene diisocyanate, toluene diisocyanate, diphenylmethanediisocyanate, bis(methylcyclohexyl) diisocyanate, oxime blockedhexamethylene diisocyanate, diethyl malonate blocked toluenediisocyanate, 3,5 dimethyl pyrazole blocked toluene diisocyanate, andcombinations thereof.
 3. The method of claim 1, wherein the blockedisocyanate comprises toluene diisocyanate blocked with 3,5 dimethylpyrazole.
 4. The method of claim 1, wherein the isocyanate comprises atleast one of a biuret, diisophorone diisocyanate, hexamethylenediisocyanate, isocyanurate of a diisocyanate, toluene diisocyanate,diphenylmethane diisocyanate, bis(methylcyclohexyl)diisocyanate, oximeblocked hexamethylene diisocyanate, diethyl malonate blocked toluenediisocyanate, toluene diisocyanate blocked with 3,5 dimethyl pyrazoleand combinations thereof.
 5. The method of claim 1, wherein theisocyanate includes a blocking agent component including at least one ofoxime, pyrazole, phenol and combinations thereof.
 6. The method of claim1, wherein curing the mixture is performed at about 80° C. to about 180°C.
 7. The method of claim 1, wherein curing the mixture is performed atabout 125° C. to about 135° C.
 8. The method of claim 1, wherein curingthe mixture takes place for at least about 10 minutes.
 9. The method ofclaim 1, wherein the polyol comprises at least one of polyethyleneglycol, polypropylene glycol, block polymers thereof, and combinationsthereof.
 10. The method of claim 1, wherein the polyol has a molecularweight equal to or between about 600 and about
 800. 11. The method ofclaim 1, wherein the polyol has a molecular weight equal to or betweenabout 800 and about
 1500. 12. The method of claim 1, wherein the polyolhas a molecular weight equal to or between about 1500 to about
 4600. 13.The method of claim 1, wherein the polyol has a molecular weight equalto or greater than about
 4600. 14. The method of claim 1, wherein themixture is substantially free of cross-linkers.
 15. The method of claim1, the mixture is substantially free of surfactants.
 16. The method ofclaim 1, wherein a catalyst is added to the mixture during mixing. 17.The method of claim 1, wherein the mixture comprises about 10 to about85 percent polyol and about 15 percent to about 90 percent by weightisocyanate.
 18. The method of claim 17, wherein the mixture furthercomprises at least one of a catalyst, solvent, rheological agent, andcombination thereof.
 19. The method of claim 1, wherein the refrigeratordoor comprises an additional substrate having a low-emissivity surfaceor a low-emissivity coating thereon.
 20. The method of claim 19, whereinthe low-emissivity surface or coating does not emit radiation aboveabout 0.7 microns.
 21. The method of claim 19, wherein thelow-emissivity surface or coating does not emit radiation between about0.7 and about 2.7 microns.
 22. The method of claim 19, wherein thelow-emissivity surface has a visible transmittance of about 70% to about90%.
 23. The method of claim 1, wherein the coating comprises ahydrophobic surface having a surface tension and a hydrophilic interiorhaving a hydrophilicity.
 24. The method of claim 23, wherein the surfacetension is less than about 30 dynes/cm.
 25. The method of claim 23,wherein the hydrophilicity is between about 20% weight gain and 150%weight gain when the coating is immersed in water for about 96 hours atabout 20 to 25° C.
 26. The method of claim 1, wherein the coating has ataber haze of less than about 10% at 100 cycles with 500 gram load and aCS-10F load using ASTM D 4060 testing.
 27. The method of claim 1,wherein substantially no fog forms on the portion of the substratehaving the coating thereon when the substrate has an initial surfacetemperature of less than about 0° C., and is then exposed to a moist airambient with a dewpoint temperature equal to or greater than the surfacetemperature for a period of time, the period of time being greater thanabout 6 seconds.
 28. The method of claim 27, wherein the period of timeis greater than five minutes.
 29. The method of claim 1, whereinsubstantially no fog forms on the portion of the substrate having thecoating thereon when the substrate has an initial surface temperature ofless than about −18° C., and is then exposed to a moist air ambient witha dewpoint temperature equal to or greater than the surface temperaturefor a period of time, the period of time being greater than about 6seconds.
 30. The method of claim 29, wherein the period of time isgreater than five minutes.
 31. The method of claim 1, wherein thecoating comprises a surfactant in an amount of less than about 3%.